Kake, AK, USA
N6117J
Piper PA-32-300
The commercial certificated pilot was conducting scheduled passenger flights. On the flight prior to the accident flight, the passengers complained of a smell the pilot thought might be exhaust. After landing, he examined the engine for exhaust leaks. Finding none, he proceeded with the return flight. While departing the airport he heard a loud bang, the passenger cabin started to fill with smoke, and he saw fire at his feet. He reduced the throttle, and landed on the airport runway. In his haste to depart the airplane, he did not turn the fuel off, and he left the electric fuel boost pump on. He said after exiting the airplane, he saw a large pool of fuel forming under the airplane, and smoke continued to emanate from the passenger cabin door. The pooled fuel ignited, burning the airplane. The passengers said they first noticed the smoke in the rear of the passenger cabin, and that the smoke propagated forward until they could no longer see the pilot. During the examination of the airplane, the NTSB investigator found that approximately a 4" X 6" piece of the right side exhaust manifold at the rear of the engine was missing. The edges of the manifold, where the piece was missing, had scalloped fractures and long straight tears consistent with fatigue fractures and failure. Additional fractures were found in other areas of the exhaust system. The hot exhaust gasses burned a hole in the heater shroud at the point where it attaches to the scat tubing which provides heated air to the vents in the rear of the passenger cabin. The hot exhaust gasses were deflected by the firewall onto the engine fuel line attached to the engine driven fuel pump mounted on the left rear of the engine, burning the fuel line through. The electric fuel boost pump provided pressurized fuel to the engine driven pump, which resulted in fuel continuing to flow and pooling on the ground. According to airplane records, the exhaust system had been inspected in accordance with the operator's approved inspection program, 2.9 flight hours prior the accident.
On June 11, 2007, about 1530 Alaska daylight time, a Piper PA-32-300 airplane, N6117J, was destroyed by fire following an emergency descent and landing after takeoff at the Kake Municipal Airport, Kake, Alaska. The airplane was being operated by L. A. B. Flying Service, Inc., Haines, Alaska, as a visual flight rules (VFR) scheduled passenger flight under Title 14, CFR Part 135, when the accident occurred. The commercial certificated pilot and the two passengers were not injured. Visual meteorological conditions prevailed, and a VFR flight plan was filed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on June 13, the pilot said on the morning of the accident, he departed Juneau, Alaska, with passengers on a scheduled flight to Kake. He said during the flight the passengers complained of a smell, or fumes, which he thought might be exhaust. After landing, he said he opened the engine cowling, and examined the engine. He said he found nothing, and decided to continue the return flight with different passengers. The pilot reported that after takeoff he turned downwind to depart the area, heard a loud bang, and white smoke started to fill the cabin. He said the engine had been at takeoff power, and he thought the engine might have been running rough. He reduced throttle, and landed on the airport runway. The pilot reported that the cabin continued to fill with smoke during landing, and that as the airplane rolled to a stop on the runway, there was fire visible at his feet on the left side of the airplane. He ushered the two passengers out and away from the airplane. He reported that in his haste to depart the airplane, he did not turn the fuel selector valve off, and the electric fuel boost pump was left on. As they moved away from the airplane, he said a pool of fuel formed under the fuselage and wings. He said smoke was coming out of the open cabin door, the pool of fuel ignited and burned the airplane. During a telephone interview with the IIC, the two passengers said when they arrived at the airport the pilot was looking inside the engine cowl. They said that the flight took off, and was still near the airport when the passenger cabin started to fill with smoke. They said they were seated in the center row of seats, and that they first noticed the smoke in the rear of the passenger cabin. They said the smoke moved forward until they could no longer see the pilot. After landing, the passengers said they exited the airplane, and saw a pool of fuel forming under the wing and fuselage. They said the fuel ignited and burned the airplane. The airplane was moved to Juneau. An examination of the wreckage by the IIC, accompanied by representatives of the FAA and airplane manufacturer, was completed on June 28. The examination of the engine showed that the engine's right side exhaust assembly had fractured, and a piece of the exhaust collector, about 4" X 6", adjacent to the aft exhaust tube was missing. The edges of the hole, where the piece was missing, had scalloped fractures and long tears. Hot exhaust gasses escaping through the hole had burned a 2-3 inch hole in the heater shroud at the point where the heater scat tubing is attached. The scat tubing ducts heated air to the firewall mounted heater control box, which in turn provides heated air to vents in the rear of the passenger cabin. The scat tubing had been burned away. The baggage/battery compartment, which is between the engine compartment and the passenger compartment, was burned away, and the battery melted, but the heat ducts under the floor of the compartment were intact. Located on the left rear of the engine, opposite the heater's scat tubing, was the engine driven fuel pump. When the electric fuel boost pump is on, pressurized fuel is delivered to the engine driven pump. The fuel hose from the electric fuel boost pump through the firewall had burned, and was disconnected at the engine driven fuel pump. According to airplane records and the operator, the airplane was inspected per the operator's approved aircraft inspection program (AAIP) on June 8, and the airplane's total time in service was 9,412.1 hours. The airplane's total time in service at the time of the accident on June 11, was 9,415 hours. Both the AAIP and the manufacturer's inspection criteria call for a detailed inspection of the entire exhaust system. During the investigation, the operator proffered the idea that the fire had started in the baggage compartment, located between the passenger cabin and the engine compartment. A laptop computer, which had been placed in the baggage compartment, and whose battery appeared to have burned away, was found in the contents of the burned compartment. The passengers stated that their baggage had contained a laptop computer and an additional battery. The investigation revealed that the original computer battery, not installed in the computer, had survived the fire intact with minimal damage. A larger, long-life battery was installed in the computer, and its case had burned away, but its 12 battery cells were identified, and recovered intact. No pieces or parts of the airplane were taken or retained by the NTSB.
A fractured exhaust manifold, which resulted in an in-flight fire, and the inadequate inspection of the airplane by the operator's maintenance personnel.
Source: NTSB Aviation Accident Database
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